The present application relates to dual-band transmitters, and, more particularly to dual-band transmitters for Remote Keyless Entry (RKE) and Passive keyless Entry Systems (PES).
In recent years, more and more car manufacturers encounter signal interference problems during the UHF signal communication of remote keyless entry (RKE) and passive keyless system (PES). In the case of a single frequency band, hopping may be used to solve this problem. However, if the interfering signal is strong and with a broad band, then frequency band hopping may not solve the interference problem. If hopping occurs in two frequency bands, then the probability of successful communication will be greatly improved. In car access systems, typically a key fob includes a transmitter for transmitting signals to a receiver that receives the signals. A dual-band transmitter in the key fob uses either two antennas or a single antenna having an RF switch to achieve dual-band emission, but these solutions require a large PCB area, and an RF switch increases cost. Further, the design of such a dual-band transmitter is very complicated.